Stop implementing ChunkedConverter.

CHANGELOG.md

+## 2.0.0
+
+**Note**: There are no APIs in 2.0.0 that weren't also in 0.9.2. Packages that
+would use 2.0.0 as a lower bound should use 0.9.2 instead—for example, `crypto:
+">=0.9.2 <3.0.0"`.

[Bob Nystrom, 2016/06/03 22:35:56]

How about a more explicit before-after? "For example, instead of "..." use
"..."."

[nweiz, 2016/06/03 22:37:38]

I'm worried that would muddy the waters more than it would help. The way it is
now, the only version constraint the user sees is the correct one. If we put
both, it would be easy to misread "instead of X use Y" as "use X instead of Y"
(or vice-versa).

+
+* `Hash` and `Hmac` no longer extend `ChunkedConverter`.
+
 ## 1.1.1
 
 * Properly close sinks passed to `Hash.startChunkedConversion()` when
   `ByteConversionSink.close()` is called.
 
 ## 1.1.0
 
 * `Hmac` and `Hash` now extend the new `ChunkedConverter` class from
   `dart:convert`.
 
@@ skipping 48 matching lines @@
 
 ## 0.9.1
 
 * Base64 convert returns an Uint8List
 * Base64 codec and encoder can now take an encodePaddingCharacter
 * Implement a Base64 codec similar to codecs in 'dart:convert'
 
 ## 0.9.0
 
 * ChangeLog starts here.